BAH!! batteries - help needed (1 Viewer)

[harniquen]

I have an assessment on batteries, iv got to compare the dry cell with mercury button cell.
I have some info but not much, especially on the mercury one

 

[Forbidden.]

Leclanché or dry cell
Zn|(ZnCl₂),NH₄Cl|MnO₂,C

Anode (-):
Zinc case
Zn(s) -----> Zn²⁺(aq) + 2e^-

Cathode (+):
Carbon rod in contact with carbon & MnO₂
NH⁴⁺(aq) + MnO₂(s) + e^- -----> NH₃(aq) + MnO(OH)(s)

Electrolyte:
Paste of NH₄Cl, ZnCl₂ (Acid electrolyte)

Cell voltage:
1.5 Volts

Uses:
Low drain appliances such as radios, torches, liquid crystal calculators, toys.


Mercury button cell

Anode (-):
Steel cap in contact with powdered Zinc
Zn(s) + 2OH^-(aq) -----> ZnO(s) + H₂O(l) + 2e^-

Cathode (+):
Steel case in contact with powdered HgO
HgO(s) +H₂O(l) + 2e- -----> Hg(l) + 2OH^-(aq)

Electrolyte:
Paste of KOH (alkaline electrolyte)

Cell voltage:
1.3 Volts

Uses:
Watches, pacemakers, hearing aids, microphones.

Source: http://www.ausetute.com.au/battery.html

 

[harniquen]

thanks very much

 

[dr baby beanie]

Mercury button cells are an excellent choice for a comparison in terms of their impact on society and the environment ...for chemistry I suppose you could say they're both non-rechargeable.


...I'll come back and finish my post later.

 

[xiao1985]

Chemistry of both cells are elegantly quoted by forbidden.

Now:

Practicality:
Button cells: inexpensive, portable, used in alot of appliances already
Mercury: more expensive, provides steady voltage (a property desired in watches and pacemakers)

Environmental:
Button: minimal. Alkalinity can cause some concern, but still minimal
Mercury: Mercury is heavy metal, which if is disposed negligently, can cause detrimental effects to environments, such as (well,) mercury poisoning.